Measured dynamic load distribution within the in situ axlebox bearing of high-speed trains under polygonal wheel–rail excitation

The dynamic load distribution within in-service axlebox bearings of high-speed trains is crucial for the fatigue reliability assessment and forward design of axlebox bearings. This paper presents an in situ measurement of the dynamic load distribution in the four rows of two axlebox bearings on a bogie wheelset of a high-speed train under polygonal wheel–rail excitation. The measurement employed an improved strain-based method to measure the dynamic radial load distribution of roller bearings. The four rows of two axlebox bearings on a wheelset exhibited different ranges of loaded zones and different means of distributed loads. Besides, the mean value and standard deviation of measured roller–raceway contact loads showed non-monotonic variations with the frequency of wheel–rail excitation. The fatigue life of the four bearing rows under polygonal wheel–rail excitation was quantitatively predicted by compiling the measured roller–raceway contact load spectra of the most loaded position and considering the load spectra as input.

A Control Simulation Method of High-Speed Trains on Railway Network with Irregular Influence

Based on the discrete time method, an effective movement control model is designed for a group of high- speed trains on a rail network. The purpose of the model is to investigate the specific traffic characteristics of high-speed trains under the interruption of stochastic irregular events. In the model, the high-speed rail traffic system is supposed to be equipped with the moving-block signalling system to guarantee maximum traversing capacity of the railway. To keep the safety of trains＇ movements, some operational strategies are proposed to control the movements of trains in the model, including traction operation, braking operation, and entering-station operation. The numerical simulations show that the designed model can well describe the movements of high-speed trains on the rail network. The research results can provide the useful information not only for investigating the propagation features of relevant delays under the irregular disturbance but also for rerouting and reseheduling trains on the rail network.

Running safety assessment method of trains under seismic conditions based on the derailment risk domain

The accurate assessment of running safety during earthquakes is of significant importance for ensuring the safety of railway lines.Currently,assessment methods based on a single index suffer from issues such as misjudgment of operational safety and difficulty in evaluating operational margin,making them unsuitable for assessing train safety during earthquakes.Therefore,in order to propose an effective evaluation method for the running safety of trains during earthquakes,this study employs three indexes,namely lateral displacement of the wheel–rail contact point,wheel unloading rate,and wheel lift,to describe the lateral and vertical contact states between the wheel and rail.The corresponding evolution characteristics of the wheel–rail contact states are determined,and the derailment forms under different frequency components of seismic motion are identified through dynamic numerical simulations of the train–track coupled system under sine excitation.The variations in the wheel–rail contact states during the transition from a safe state to the critical state of derailment are analyzed,thereby constructing the evolutionary path of train derailment and seismic derailment risk domain.Lastly,the wheel–rail contact and derailment states under seismic conditions are analyzed,thus verifying the effectiveness of the evaluation method for assessing running safety under earthquakes proposed in this study.The results indicate that the assessment method based on the derailment risk domain accurately and comprehensively reflects the wheel–rail contact states under seismic conditions.It successfully determines the forms of train derailment,the risk levels of derailment,and the evolutionary paths of derailment risk.

Minimum Curve Radii for High-Speed Trains, Including the Gyroscopic Moments of the Wheels

This paper studies the title problem including an analysis of the gyroscopic effects of the wheels of a rail-car travelling at high-speed around a level, horizontal curve. The analysis is based upon the fundamental principles of dynamics. The result is a design formula for the minimum curve radius needed to prevent derailment. Aside from the rail car geometric and physical properties, the minimum curve radius depends upon the square the train speed. An illustrative example shows that the wheel gyroscopic effect is destabilizing and additive to the centrifugal force derailment tendency. From a track design perspective, however, the gyroscopic effect is relatively small compared with the centrifugal force effect.

Numerical study of wheel–rail adhesion performance of new-concept high-speed trains with aerodynamic wings

Wheel–rail adhesion is a complex tribological problem of wheel–rail rolling contact and is closely related to the operational safety of high-speed trains.A new design concept of high-speed trains was recently proposed with an expectation of a reduction of equivalent weight and total energy consumption by installing aerodynamic wings(aero-wings)on the roof,but it was accompanied by the disadvantage of deteriorating wheel–rail adhesion performance.In this study,a comprehensive multibody dynamics(MBD)model of the high-speed train with predesigned aero-wings is established using the commercial software SIMPACK,in which the real aerodynamic characteristics of the train are taken into account.The available adhesion and adhesion margin are employed to evaluate the wheel–rail adhesion performance.The influences of aero-wing lift,train speed,and contact conditions on the wheel–rail adhesion level are discussed.The results show that the load transfer caused by the action of aerodynamic load and braking torque was the main reason for the inconsistent adhesion condition of four wheelsets.The influences of aero-wing lift and train speed on the wheel–rail adhesion performance are coupled;the available adhesion of both motor car and trailer is negatively correlated with aero-wing lift and train speed under all contact conditions,while the variation law of adhesion margin with train speed shows differences under different contact conditions.When the wheel–rail interface was polluted by a‘third-body medium’such as water and oil,the wheel–rail adhesion performance was dramatically reduced and the wheelset tended to reach adhesion saturation and slide.However,track irregularity had little effect on the adhesion performance and could be ignored to save calculation time.These results are of positive significance for reducing the wheel idling or sliding phenomenon and to ensure the safe operation of high-speed trains with aero-wings.

Rail temperature rise characteristics caused by linear eddy current brake of high-speed train

The rail temperature rises when the linear eddy current brake of high-speed train is working, which may lead to a change of rail physical characteristics or an effect on train operations. Therefore, a study concerning the characteristics of rail temperature rise caused by eddy current has its practical necessity. In the research, the working principle of a linear eddy current brake is introduced and its FEA model is established. According to the generation mechanism of eddy current, the theoretical formula of the internal energy which is produced by the eddy current is deduced and the thermal load on the rail is obtained. ANSYS is used to simulate the rail temperature changes under different conditions of thermal loads. The research result shows the main factors which contribute to the rising of rail temperature are the train speed, brake gap and exciting current. The rail temperature rises non-linearly with the in- crease of train speed. The rail temperature rise curve is more sensitive to the exciting current than the air gap. Moreover, the difference stimulated by temperature rising between rails of 60 kg/m and 75 kg/m is presented as well.

Wind tunnel tests on aerodynamic characteristics of vehicles on same-storey highway and rail bridge under crosswind

In recent years,the safety and comfort of road vehicles driving on bridges under crosswinds have attracted more attention due to frequent occurrences of wind-induced disasters.This study focuses on a container truck and CRH2 high-speed train as research targets.Wind tunnel experiments are performed to investigate shielding effects of trains on aerodynamic characteristics of trucks.The results show that aerodynamic interference between trains and trucks varies with positions of trains(upstream,downstream)and trucks(upwind,downwind)and numbers of trains.To summarize,whether the train is upstream or downstream of tracks has basically no effect on aerodynamic forces,other than moments,of a truck driving on windward sides of bridges(upwind).In contrast,the presence of trains on the bridge deck has a significant impact on aerodynamic characteristics of a truck driving on leeward sides(downwind)at the same time.The best shielding effect on lateral forces of trucks occurs when the train is located downstream of tracks.Finally,the pressure measuring system shows that only lift forces on trains are affected by trucks,while other forces and moments are primarily affected by adjacent trains.

Influence of Rail Fastening System on the Aerodynamic Performance of Trains under Crosswind Conditions

The large number and dense layout of rail fastening can significantly affect the aerodynamic performance of trains.Utilizing the Improved Delayed Detached Eddy Simulation(IDDES)approach based on the SST(Shear Stress Transport)k-ωturbulent model,this study evaluates the effects of the rail fastening system on the aerodynamic force,slipstream and train wake under crosswind conditions.The results indicate that in such conditions,compared to the model without rails,the rail and the fastening system reduce the drag force coefficient of the train by 1.69%,while the lateral force coefficients increase by 1.16%and 0.87%,respectively.The aerodynamic force can be considered virtually unchanged within the error allowance.However,the rail and the fastening system cause an inward shift of the negative pressure center on the leeward side of the train.The peak slipstream velocity near the ground in the rail and rail fastening system model is significantly lower than that in the situation without rails.Additionally,the rail and the fastening system not only induce two displacements in the vortex structure of the train but also accelerate the dissipation of shedding vortex and the rapid decrease of turbulent kinetic energy.

Rolling Along China steps into the high-speed rail age as two new projects get final government approval

The Beijing-Shanghai railway, linking the two biggest cities in China, is the busiest railway in the world, having an annual cargo capacity of 120 million tons and transporting 30 million passengers. Connecting two economically developed regions-the Yangtze Delta and Circum-Bohai (sea) area-the railway

Changing Trains

“Harmony” proves more than just a name for commuters on China＇s new high-speed train.

Dynamic analysis of a high-speed train operating on a curved track with failed fasteners

A high-speed train-track coupling dynamic model is used to investigate the dynamic behavior of a high-speed train operating on a curved track with failed fasteners. The model considers a high-speed train consisting of eight vehicles coupled with a ballasted track. The vehicle is modeled as a multi-body system, and the rail is modeled with a Timoshenko beam resting on the discrete sleepers. The vehicle model considers the effect of the end connections of the neighboring vehicles on the dynamic behavior. The track model takes into account the lateral, vertical, and torsional deformations of the rails and the effect of the discrete sleeper support on the coupling dynamics of the vehicles and the track. The sleepers are assumed to move backward at a constant speed to simulate the vehicle running along the track at the same speed. The train model couples with the track model by using a Hertzian contact model for the wheel/rail normal force calculation, and the nonlinear creep theory by Shen et al. (1984) is used for wheel/rail tangent force calculation. In the analysis, a curved track of 7000-m radius with failed fasteners is selected, and the effects of train operational speed and the number of failed fasteners on the dynamic behaviors of the train and the track are investigated in detail. Furthermore, the wheel/rail forces and derailment coefficient and the wheelset loading reduction are analyzed when the high-speed train passes over the curved track with the different number of continuously failed fasteners at different operational speeds. Through the detailed numerical analysis, it is found that the high-speed train can operate normally on the curved track of 7000-m radius at the speeds of 200 km/h to 350 km/h.

Development and validation of a model for predicting wheel wear in high-speed trains

In this paper, we present a comprehensive model for the prediction of the evolution of high-speed train wheel profiles due to wear. The model consists of four modules： a multi-body model implemented with the commercial multi-body software SIMPACK to evaluate the dynamic response of the vehicle and track; a local contact model based on Hertzian theory and a novel method, named FaStrip （Sichani et al., 2016）, to calculate the normal and tangential forces, respectively; a wear model proposed by the University of Sheffield （known as the USFD wear function） to estimate the amount of material removed and its distribution along the wheel profile; and a smoothing and updating strategy. A simulation of the wheel wear of the high-speed train CRH3 in service on the Wuhan-Guangzhou railway line was performed. A virtual railway line based on the statistics of the line was used to represent the entire real track. The model was validated using the wheel wear data of the CRH3 operating on the Wuhan- Guangzhou line, monitored by the authors＇ research group. The results of the predictions and measurements were in good agreement.

新型高铁列车推进高铁运输与现代物流的融合问题

现代物流已逐渐成为企业创造利润的主要途径,也是企业核心竞争力的具体体现,保障了整个国民经济的高效运行。国民经济的发展对铁路运输业提出了更高、更新的要求。高铁货运具有成本低、耗时短、准时率高等诸多优势,也不像航空货运极易受冰冻雨雪等天气因素的影响,因而实施高速铁路货运是经济社会发展的必然产物,可以大幅提高货物的运输效率,是实现铁路运输与现代物流的融合与发展的关键路径。由于中国庞大的货运需求及铁路自身的限制因素,高铁货物运输存在供需矛盾及自身的结构性矛盾。采用定性及定量分析相结合的方法,从中车公司开发的3X餐货两用车的特性和优势入手,通过定性分析指出该系列动车组是解决现存货物运输问题的有效途径;以京沪高速铁路线为算例,定量地分析后认为在主要高铁线路运行新型餐货两用车预期带来的经济效益。研究结果表明:中车公司研发的3X新型高铁列车的投入运营,不仅在客运方面具有巨大的经济效益,在货运方面也会积极推进高铁运输与现代物流的融合,是适应中国国情及铁路发展前景的铁路产品,能够为社会带来巨大的经济和社会效益。

轨道交通特色信息类创新人才培养体系探索

该文围绕轨道交通信息"采集""传输""处理"及"控制"的全过程,介绍了新一代信息技术交叉融合的轨道交通信息类创新人才培养的思路及方法。以学生工程实践能力和综合创新能力培养为主线,通过搭建多学科、多专业交叉融合的综合实验平台,引入"实验群"概念对实验室和实验课程进行重新组合和划分,建立起多学科融合、多层次实验教学,多维度实践创新的人才培养体系,提升了学生的创新能力和专业核心竞争力,满足了轨道交通信息化、现代化和国际化发展的要求。

轨道交通减振扣件对列车稳定性影响对比测试

为研究GH-1轨道交通新型减振扣件对列车稳定性的影响,进行轨道行车稳定性试验,测试列车通过不同轨道减振扣件区时转向架及车厢的横向和垂向振动加速度,与现行国际规范及国家标准规定的列车运行安全性和平稳性指标进行对比,并比较分析列车在不同扣件区的振动加速度响应。结果表明,列车通过GH-1新型轨道减振扣件区时,列车安全性和平稳性能够满足标准规定的限值,且车体的横向和垂向振动响应以及转向架的横向振动响应相对于列车通过国内常用的DT系列某型号扣件区时更小,列车稳定性更好。该结果对GH-1轨道交通新型减振扣件的使用安全具有参考价值。

新型列控系统列车追踪间隔的优化及效能评估

为了解决地铁列车运力不足,缩短列车追踪间隔,提出了新型列控系统、相对移动闭塞和协同运行三者相结合的方法,构建了列车通信协同运行模型。在该模型下,精细化前后列车冲突区域,对正线和站后折返最小追踪间隔分别优化建模,提出缩短追踪间隔的行车策略。经实际线路仿真计算,相比基于通信的列车运行控制系统(communication based train control,CBTC)列车通过能力提升了32.3%,且4A编组可以满足79.9 s的行车间隔。考虑缩短行车间隔对运营效能的影响,将运营效能量化为运输率、满载率、单位能耗、等车时间,对不同行车方案进行评估。结果表明,对于单向小时断面客流量小于6.4万的线路,通过调节行车间隔,4A编组在满足满载率下,比6A、8A编组能耗更小,等车时间更短。

中低运量新型轨道交通信号系统方案研究

结合中低运量新型轨道交通的工程特点和运营需求分析,探讨与线路运能相匹配的列车运行安全防护方案,明确选择列控制式时需要考虑的主要因素;分析了与运营管理模式相适应的信号系统架构设计原则,提出以地面列控为主的精简型信号系统架构及设备配置方案,有利于降低信号系统的建设与运维成本。

地铁列车车体技术研究

城轨交通高质量可持续发展是交通强国建设的重要内容。欧盟、日本在轨道车体领域进行集团式产品和技术开发已持续推进近10年,其技术创新具有全局性、整体性和系统性。为提升我国地铁列车技术整体水平,中国中车在相关部委支持下开展了系列化中国标准地铁列车的研制。针对地铁车体设计要素和既有技术体系进行了调研,分析了车体顶层设计和融合技术的重要性,探讨了中国标准地铁车体技术创新平台搭建要素;介绍了标准地铁车体结构继承性、设计优化和性能提升情况、试验验证结果和设计简统成果;论述了车体新材料、新工艺、新结构等技术创新的方向与目标。结果表明,标准地铁车体结构符合技术规格书要求,可满足行业实际应用需求,对地铁车体进行前瞻性和基础性技术研究仍具有迫切性和必要性。

新工科下轨道交通车辆工程本科生培养方案思索——同济大学车辆工程(四年制)本科建设

当前,世界范围内新一轮科技革命和产业变革正在兴起,不断催生新技术、新业态和新产品,迫切需要培养造就一大批创新型工程人才。新工科建设是对新一轮科技革命和产业变革的主动响应,本文在"新工科"背景下,对同济大学车辆工程(四年制)本科生培养模式及培养方案进行探究,对如何培养高素质、多学科交叉型人才做了进一步的探讨,为新工科下高校的轨道交通车辆工程复合型人才培养体系提出了基本思路。

西部陆海新通道班列品牌建设研究

我国正在构建以共建“一带一路”为统领的全方位对外开放格局,与沿线国家间经贸往来发展迅速,跨境跨区域多式联运走廊不断完善,为我国铁路构筑国际集装箱物流品牌带来难得的发展机遇。通过分析西部陆海新通道班列品牌的建设意义,在总结借鉴国际知名多式联运品牌建设经验的基础上,提出西部陆海新通道班列品牌建设总体思路,围绕提升西部陆海新通道班列产品的知名度、扩大品牌影响力的目标,研究提出品牌建设对策与配套保障措施,形成西部陆海新通道班列品牌建设方案,为助力西部陆海新通道班列发展,加快构建我国与东盟间高效畅通的铁路多式联运通道提供支撑。